Project Abstract This is a request for a diversity supplement to the existing grant R35GM133470 to hire Jorge Martinez as a post-doctoral scholar. Jorge Martinez is an outstanding Ph.D. candidate in the laboratory of Jeremy Smith. When he joins our group, Jorge will work on studying the fundamental effects of anionic charges on coordination complexes, particularly oxo complexes. This proposed research involves the investigation of distal anion effects on the properties of transition metal oxo complexes. Transition metal oxo species are invoked as central intermediates in a wide variety of enzymatic oxidations. This centrality has motivated substantial efforts at understanding their structure and function. Molecular model complexes have provided significant insights into oxo complexes by providing systems where hypotheses can be rationally and systematically studied. Nevertheless, it is becoming increasingly apparent that classic systems used to model oxo intermediates, which typically feature strongly donating anionic ligand sets, do not mimic the electronic structures or reactivities of some of the most interesting enzymatic active sites. Against this backdrop, recent results have underscored the importance of secondary coordination sphere effects in the function of oxo species. These studies have primarily focused on hydrogen bonding interactions. In this research program, we aim to investigate an alternative secondary coordination sphere influence, namely that of distal anionic charges. Enzymatic active sites can be highly charged and this effect can strongly influence the reactivity of different oxo species. However, the effect of the incorporation of distal charges has not been systematically investigated. We aim to rationally incorporate distal anions onto model oxo complexes in order to study the effect of anionic charge on the reactivity and properties of transition metal oxo species. Jorge's project will involve a fac-chelating ligand where the number and position of negative charges can be systematically controlled. Furthermore, the system that Jorge will synthesize will enable tuning of the dipole or electric field of systems while also changing the overall charge of the system. Jorge will investigate how these variable affect fundamental properties such as redox-potential, backbonding, basicity, as well as more exotic phenomena such as O-centered radical character. Jorge will then be able to link these properties and the effects of anionic charges to important reactions such as C?H activation and oxygen evolution. In parallel with this research effort, there will be a comprehensive and curated training program to prepare Jorge for a career as a PI at a major research institution. This will involve training in communication, both written and verbal, as well as new instrumental and analytical techniques. Furthermore, there is a multi-component plan aimed at networking interactions for Jorge with the community more broadly and with other faculty at UChicago and other institutions in particular.